In a sauce pan, add the water of juice, sugar, and cranberries. Bring to a simmer and simmer for 10 minutes until all the cranberries pop and the sauce starts to thicken.
Add in the raspberries and simmer for another 3 minutes. Remove from heat and allow to cool. Serve immediately or refrigerate until ready to use. This can also be frozen for up to 2 months. Makes 2 1/2 cups.